Pre- and post–bed rest volumetric MRI and physiologic measurements (group mean and SD)
| Measurements | Pre-bed rest | Post-bed rest | P Value |
|---|---|---|---|
| ICV (mL) | 1426 ± 105 | 1425 ± 105 | .91 |
| Gray matter (mL) | 603.8 ± 40.8 | 615.1 ± 50.4 | .18 |
| White matter (mL) | 546.0 ± 58.4 | 540.8 ± 51.5 | .48 |
| CSF (mL) | 185.8 ± 15.0 | 186.6 ± 16.1 | .83 |
| Ventricle volume (mL) | 15.45 ± 5.52 | 15.0 ± 4.31 | .62 |
| Plasma volume (mL) | 2.63 ± 0.38 | 2.30 ± 0.46 | .006 |
| Blood volume (mL) | 4.57 ± 1.02 | 4.08 ± 1.11 | .004 |
| Urine cortisol (μg/dL) | 2.63 ± 0.97 | 3.58 ± 1.06 | .14 |